Ever since surf-riding boards and sailing boards (hereinafter referred to merely as "boards") have been built, their builders have tried to obtain a more perfect adaption to different demands by providing the boards with an individual form. As variables, in the first place, the length, the width, the outward shape of the board, the disposition of the thickness (volume), the shape of the part below the water line in the longitudinal direction, and the shape of the part below the water line in cross section have been studied. These variables can be combined in many different ways to influence the sailing qualities of the board.
Also, a flexible design of the shape of the part below the water line in the longitudinal direction has been considered. In this connection, see the magazine Surf No. 8/1985 at pages 30 and 31 (Delius Klasing & Co., Siekerwall 21, 4800 Bielefeld, West Germany). However, so far a design as depicted in that magazine article could not be realized.
By an exploitation of the variables listed above, a rather good adaption of the boards to the specific requirements (speed, maneuvering capability, all around qualities, rocking stability, etc.) could be reached. However, this adaption was reached at the expense of other qualities. The more a board was constructed in view of a certain task, the more other aspects had to be neglected.